* {
    margin: 0;
    padding: 0;
}

.big {
    width: 1000px;
    height: 800px;
    margin: 50px auto;
    background-color: rgb(118, 235, 200);
    box-sizing: border-box;
}

h1 {
    font-size: 50px;
    color: black;
    text-align: center;
}

.small {
    box-sizing: border-box;
    margin: 50px 180px;
    text-align: center;
    width: 640PX;
    height: 640px;
    background-color: rgb(118, 235, 200);
    display: inline-block;
    text-align: center;
    overflow: hidden;
}

.a {
    box-sizing: border-box;
    width: 300px;
    height: 300px;
    background-color: #fff3e2;
    border: double 6px #d05a54;
    text-align: center;
    float: left;
    text-align: center;
    padding-top: 30px;
    margin-bottom: 5px;
}

.b {
    box-sizing: border-box;
    width: 300px;
    height: 300px;
    background-color: #fff3e2;
    text-align: center;
    float: right;
    text-align: center;
    padding-top: 30px;
    border: double 6px #d05a54;
    margin-bottom: 5px;
}

.c {
    box-sizing: border-box;
    width: 300px;
    height: 300px;
    background-color: #fff3e2;
    text-align: center;
    float: left;
    text-align: center;
    padding-top: 30px;
    border: double 6px #d05a54;
    margin-top: 25px;
}

.d {
    box-sizing: border-box;
    width: 300px;
    height: 300px;
    background-color: #fff3e2;
    text-align: center;
    float: right;
    text-align: center;
    padding-top: 30px;
    border: double 6px #d05a54;
    margin-top: 25px;
}